The story about a man who suddenly can no longer die is pretty interesting. Torchwood will also - tell less sophisticated story, but rather confront the viewer with his own thoughts - as in Season 3: What should be done logically? What is morally right? As I myself would deal with it. And you can tell the same, the one is the own skin the next again.
In the middle of the season is a little elongated. It brought many people to the game that are not somehow more important. They come and go. Many plots are not cleared up and the reason for everything actually not. But that's in those stories anyway mostly rather difficult.
I have the season thanks to a flu in three days looked through and found them consistently quite exciting. However, I would be delighted if Torchwood would drive back to its original patterns and again make an entire season with single episodes would ..